#include "../../../include/RenderBackend/OpenGL/DeviceMemory.hpp"
#include "../../../include/RenderBackend/OpenGL/opengl.hpp"

namespace amalgine
{
    u32 getOpenglStorageType(DeviceMemory::StorageType storageType)
    {
        switch(storageType)
        {
            case DeviceMemory::StorageType::STATIC:     return GL_STATIC_DRAW;
            case DeviceMemory::StorageType::DYNAMIC:    return GL_DYNAMIC_DRAW;
            case DeviceMemory::StorageType::STREAM:     return GL_STREAM_DRAW;
        }
    }
    
    u32 getOpenglPrimitiveType(DeviceMemory::PrimitiveType primitiveType)
    {
        switch(primitiveType)
        {
            case DeviceMemory::PrimitiveType::TRIANGLE:     return GL_TRIANGLES;
        }
    }
    
    u32 getPrimitiveTypePointsPerVertices(DeviceMemory::PrimitiveType primitiveType)
    {
        switch(primitiveType)
        {
            case DeviceMemory::PrimitiveType::TRIANGLE:     return 3;
        }
    }
    
    DeviceMemory::DeviceMemory() : primitiveType(0), numVertices(0)
    {
        glGenBuffers(1, &vertexBufferObjectId);
    }
    
    DeviceMemory::~DeviceMemory()
    {
        glDeleteBuffers(1, &vertexBufferObjectId);
    }
    
    void DeviceMemory::operator delete(void *data)
    {
        free(data);
    }
    
    void DeviceMemory::use() const
    {
        // TODO: Bind vao here?
        glBindBuffer(GL_ARRAY_BUFFER, vertexBufferObjectId);
    }
    
    void DeviceMemory::copy(const DataView<f32> &data, StorageType storageType, PrimitiveType primitiveType)
    {
        glBindBuffer(GL_ARRAY_BUFFER, vertexBufferObjectId);
        glBufferData(GL_ARRAY_BUFFER, data.getByteSize(), data.data, getOpenglStorageType(storageType));
        this->primitiveType = getOpenglPrimitiveType(primitiveType);
        numVertices = getPrimitiveTypePointsPerVertices(primitiveType);
    }
    
    void DeviceMemory::draw()
    {
        if(primitiveType == 0)
            throw DeviceMemoryEmpty("Unable to draw buffer as no data has been copied to device memory");
        glDrawArrays(primitiveType, 0, 3);
    }
}